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Rat eradication comes within a whisker! A case study of a failed project from the South Pacific.

Published version
Peer-reviewed

Repository DOI


Type

Article

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Authors

Nichols, HJ 
Churchyard, T 
Brooke, M de L 

Abstract

To enhance their conservation value, several hundred islands worldwide have been cleared of invasive alien rats, Rattus spp. One of the largest projects yet undertaken was on 43 km(2) Henderson Island in the Pitcairn group, South Pacific, in August 2011. Following massive immediate mortality, a single R. exulans was observed in March 2012 and, subsequently, rat numbers have recovered. The survivors show no sign of resistance to the toxicant used, brodifacoum. Using pre- and post-operation rat tissue samples from Henderson, plus samples from around the Pacific, we exclude re-introduction as the source of continued rat presence. Microsatellite analysis of 18 loci enabled comparison of genetic diversity of Henderson rats before and after the bait drop. The fall in diversity measured by allele frequency change indicated that the bottleneck (N e) through which the breeding population passed was probably around 50 individuals, representing a census population of about 60-80 animals. This is the first failed project that has estimated how close it was to success.

Description

Keywords

Henderson Island, Pitcairn Islands, Rattus exulans, brodifacoum, genetic diversity, heterozygosity

Journal Title

Royal Society Open Science

Conference Name

Journal ISSN

2054-5703
2054-5703

Volume Title

3

Publisher

The Royal Society
Sponsorship
The Darwin Initiative funded much of the RSPB’s work on Henderson Island and therefore sample collection and analysis, the latter also supported by the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands.